The present invention is related to intraocular lenses (IOLs). More particularly, the invention relates to such lenses which provide substantial advantages of both monofocal IOLs and multifocal IOLs.
Currently produced or conventional monofocal IOLs provide excellent optical quality for distance vision. Thus, such monofocal IOLs are produce with a single vision correction power, that being a vision correction power for distance or distance vision. However, such conventional monofocal IOLs do not provide sufficient near vision correction for reading or other situations where near vision is required.
One approach to providing near vision correction is currently in commercial use and is known generically as xe2x80x9cmultifocal IOLsxe2x80x9d. Such multifocal IOLs are produced with a plurality of optical powers, for example, a distance vision correction power and a near vision correction power. Although such lenses have proven to be quite effective in providing the desired range of vision correction power, they may not be totally acceptable to some patients due to the simultaneous vision characteristics of such lenses which may produce halo/glare phenomena.
An additional approach to providing the patient with a range of vision correction powers has been suggested and is commonly known as an xe2x80x9caccommodating IOLxe2x80x9d. This type of IOL is designed to specifically provide both distance and vision correction powers. For example, the accommodating IOL may provide for the axial movement of a monofocal optic to vary the focus of an image on the retina. Such accommodating IOLs often are limited by the amount of movement required to produce adequate accommodation. For example, an accommodating IOL to be substantially effective should produce from 2.5 diopters to 3.5 diopters of add power to result in adequate near vision. There may not be adequate accommodative mechanisms remaining in the pseudo-phakic eye to move a monofocal lens the desired amount.
There continues to be a need to provide IOLs which are effective to provide both distance vision correction and near vision correction.
New IOLs have been discovered. The present IOLs take advantage of employing an optic adapted to have two different configurations to enhance the accommodation achievable in the eye in response to normal accommodative stimuli. Thus, the present IOLs have a first configuration in which the optic of the IOL has a monofocal distance vision correction power, for example, with the IOL in its resting state. In this first configuration, the present IOLs retain the excellent vision characteristics of a conventional monofocal distance vision correction IOL. However, the optics of the present IOLs are further adapted to have a second configuration to provide a plurality of different optical powers, for example, a near vision correction power in addition to a far or distance vision correction power.
Thus, the present lenses provide for vision correction or focusing for both near objects and far or distance objects. The negative aspects of simultaneous vision which occur with multifocal IOLs, such as night driving and the halo/glare phenomenon, are reduced, or even eliminated, with the present IOLs in the monofocal distance state or configuration. With the present IOL in the multifocal or second configuration, adequate near vision, for example, up to about 3.5 diopters in add power, are provided. The present IOLs are substantially not limited by the amount of accommodative ability remaining in the pseudo-phakic eye. The shape or configuration of the IOL is selectively changed for near vision by the patient during accommodation, for example, by the patient focusing from distance to near.
The present IOLs are relatively straightforward in construction and to manufacture or produce, can be implanted or inserted into the eye using systems and procedures which are well known in the art, and function effectively with little or no additional treatment or medications being required.
In one broad aspect of the present invention, IOLs for use in a mammalian eye are provided. Such IOLs comprise an optic adapted to focus light toward a retina of a mammalian, e.g., human, eye. The optics are further adapted to have a first configuration to provide a single optical power and a second configuration to provide a plurality of different optical powers. The optics advantageously are moveable between the first configuration and the second configuration. Preferably, the optics are moveable in cooperation with the mammalian eye between the first configuration and the second configuration. For example, the optic can be reshaped or is reshapable between the first configuration and the second configuration. Such reshaping preferably occurs in cooperation with the mammalian eye.
The present IOLs include means acting to at least assist in moving the optic into the second configuration, for example, in moving the optic between the first and second configuration. Such means can be, and preferably is, part of the optic of the present IOLs. Preferably, such means acts to do at least one of: facilitate the movement of the optic in cooperation with the mammalian eye, and inhibit the movement of the optic in cooperation with the mammalian eye. Thus, for example, the means can be provided as part of the optic to at least assist in controlling the reshaping or configuring of the optic between the first configuration and the second configuration.
In one embodiment, the optic has an outer surface and the means is located in proximity to the outer surface. For example, the outer surface may be part of an outer layer or portion substantially surrounding a core. The outer layer or portion can be specifically configured to provide a monofocal vision correction with the optic in the first configuration, such as with the optic in the rest position, and/or desired multifocal vision correction powers with the optic in the second configuration, such as with the optic being reshaped, for example, compressed, by the action of the mammalian eye.
The optic preferably includes at least one region adapted and positioned to do at least one of: facilitate the movement of the optic in cooperation with the mammalian eye, and inhibit the movement of the optic in cooperation with the mammalian eye. This at least one region preferably is located in proximity to the outer surface of the optic. For example, the at least one region may be in the form of an annulus or band around the optical axis of the optic. This region may have reduced thickness or rigidity or may be otherwise weakened so that the optic, under the influence of the mammalian eye, can move to a second configuration and provide a different optical power at that region. Alternately, or in addition, a region may be provided which has increased thickness or rigidity or may be otherwise strengthened so that even under the influence of the mammalian eye, the optic is inhibited, or even substantially prevented, from having a different optical power at the region.
Advantageously, the optic includes a plurality of such regions. Such region or regions may be part of the outer layer or portion of the optic or may be otherwise located at or near the outer surface of the optic.
In a very useful embodiment, the optic includes an inner core and an outer layer or portion adjacent to the inner core, preferably with the inner core being more deformable than the outer layer. In this embodiment, the outer layer or portion preferably is structured to do at least one of: facilitate the movement of the optic in cooperation with the movement of the mammalian eye, and inhibit the movement of the optic in cooperation with the mammalian eye, for example, in a manner as described elsewhere herein.
The present IOLs preferably are fabricated from one or more flexible, fully cured deformable polymeric materials. For example, an outer layer or portion may be provided that selectively deforms due to prescribed varied wall thicknesses or hinged areas. The outer portion or shell preferably encases or surrounds a core, preferably made of a more easily or readily deformable material, for example, a polymeric material which is more easily deformable relative to the polymeric material from which the outer layer or portion is made. The core preferably comprises a first polymeric material and the outer layer or portion comprises a different, second polymeric material. Although it is not necessary, it is preferred that the refractive indexes of the first and second polymeric materials be substantially the same, that is within about 7% or about 5% in refractive index of each other.
The optics of the present IOLs preferably comprise at least one polymeric material, and in a very useful embodiment at least two different polymeric materials. Overall, the optic preferably is sufficiently deformable to be inserted through a small incision into the eye. Upon contraction by the ciliary muscle due to accommodation, the optic is compressed or squeezed circumferentially. The optic is deformed or reshaped into a prescribed shape that results in a multifocal surface, preferably a multifocal anterior surface. This multifocal surface advantageously is a refractive surface that provides for near vision and preferably distance or far vision.
In one embodiment, the present IOLs in the second configuration provide only two optical powers, that is the present IOLs are bifocal in character, for example, providing for near vision correction in a central portion and distance vision radially outwardly of the central portion of the optic, such as near or along the periphery of the optic. Of course, the lenses can be produced so that the second configuration provides more than two optical powers, for example, a more elaborate multifocal surface, such as that described in Portney U.S. Pat. No. 5,225,858, the disclosure of which is incorporated in its entirety herein by reference.
In a particularly useful embodiment, the optic has an optical axis, and at least one of the plurality of different optical powers, in the second configuration, is provided in an annular region around the optical axis.
In one embodiment, the IOL further comprises a force transfer assembly secured to and extending radially outwardly from the optic. The force transfer assembly is adapted, when the IOL is located in the mammalian eye, to transfer a force exerted by the eye to the optic, thereby to facilitate the movement of the optic between the first configuration and the second configuration. Advantageously, the force transfer assembly includes an end extending from the optic adapted to contact a capsular bag of the mammalian eye when the IOL is located in the mammalian eye.
The reshaping or deformation of the optic from the first to the second configuration can cause an axial movement of the optic which has an additional effect on the accommodative power of the optic. The overall accommodative power of the optic in accordance with the present invention preferably is increased beyond the simple axial movement of a single configuration monofocal lens because of the first and second configurations of the present optics.
It should be noted that the force transfer assembly is not essential in accordance with the present invention. The optic can be sized and configured to fit within the capsular bag and to contact the capsular bag, in particular the periphery of the capsular bag, so that the force exerted on the capsular bag by the ciliary muscle can be transferred directly to the optic of the present IOL. Such IOLs in which the optics are sized and configured to contact the peripheral capsular bag are very effective in being reshaped to provide the desired vision correction power or powers. In addition, substantially filling the capsular bag volume with a deformable optic reduces the risk of decentration or tilt of the lens system in the eye, relative to lens systems in which the optic does not substantially fill the capsular bag volume. Providing for a reduced risk of decentration is highly advantageous, for example, as the capsular bag contracts. Even if the contraction of the capsular bag is asymmetric, for example, because the zonules are not of uniform strength, the elastic properties of the optic mitigate against this asymmetry and reduce the risk of decentration.
Substantially filling the capsular bag volume, as described above, may reduce the risk of posterior capsular opacification (PCO) particularly if the posterior surface of the optic remains in contact with the posterior wall of the capsular bag during all states of accommodation.
In a very useful embodiment, the present IOLs are deformable for insertion into the mammalian eye through a relatively small incision, for example, on the order of about 3.5 mm or less. Thus, the optic, and the force transfer assembly, if present, are deformable for insertion through a small incision into the eye. Such IOLs regain their original undeformed condition rapidly after being inserted into the mammalian eye. However, it is preferred that the entire IOL be sufficiently deformable to be passed through an incision in the eye which is less than the diameter of the IOL in its undeformed condition.
The present optics may be made of any suitable materials of construction. For example, the present optics may be made of one or more polymeric materials employing techniques used in manufacturing conventional polymeric material IOLs. Examples of the materials from which the present optics can be made include, without limitation, acrylic polymeric materials, silicone polymeric materials, and the like and combinations thereof. Although combinations of different polymeric materials may be employed, the present optics preferably are made of different polymeric materials of the same general chemical family. For example, the inner portion or core of the optic may be made of one silicone polymeric material while the outer portion or layer or other means is made of a different silicone polymeric material. Similarly, the core of the optic can be made of one acrylic polymeric material while the outer layer or other means is made of a different acrylic polymeric material. In any event, the present optics preferably are made of compatible materials of construction, that is materials which can be used to produce an effective IOL which remains as an intact structure in the eye without significant deterioration for periods of time extending for at least about 20 or about 25 years or more.
In one embodiment, the inner portion or core of the present optics is made of a very low modulus silicone polymeric material, while the outer portion or layer or other means is made of a higher strength silicone polymeric material. For instance, the outer portion may have a tensile yield strength of 625 psi, as measured using an SLJ-2 as a benchmark, and have a tensile modulus of elasticity at 150% elongation of 400 psi. To illustrate, the core of the optic can be composed of a silicone polymeric elastomer with the following material properties:
Optically clear;
Refractive index of at least about 1.40;
Shore A hardness of about 0; and
At least about 1000% elastic elongation.
The outer layer or other means of the present optics can be made of a different silicone elastomer with the following material properties:
Optically clear;
Refractive index of at least about 1.40;
Shore A hardness in a range of about 0 to about 45; and
An elastic elongation of at least about 150%, preferably in a range of about 150% to about 400%.
The outer layer or other means can be made of widely varying materials. Examples include, without limitation, rigid and foldable acrylic polymeric materials, rigid and foldable non-acrylic polymeric materials, deformable or foldable silicone polymeric materials and the like and combinations thereof. The outer layer or other portion can be hydrophobic or hydrophilic.
Many materials which meet the above-noted criteria are conventional and well known in the art. Therefore, a detailed description of such compositions is not presented here.
However, by way of illustration, the following materials of construction, based on constituent monomeric components, is presented.
The present optics are conveniently produced using conventional and well known techniques, such as molding techniques. In one embodiment, the outer layer or other means, for example, one or more annular bands of material, is produced in a separate mold and then placed into a mold into which is placed the monomeric or partially polymerized monomeric mixture of the core precursors. The combination is then heated to elevated temperatures, for example on the order of about 40xc2x0 C. to about 100xc2x0 C., and the combination is allowed to cure, preferably for about one hour to about 24 hours. The material in the mold is then post-cured, preferably at a temperature in the range of about 70xc2x0 C. to about 130xc2x0 C., for a period of time, preferably for about two hours to about 30 hours. After curing (and post-curing), the mold is disassembled and the molded optic recovered.
The force transfer assembly, if present, can be made or provided separately and then coupled to the optic or lens body, for example, in a mold in which the optic is cured or post-cured. Alternately, the force transfer assembly can be coupled to the lens body after the lens body is formed. Conventional techniques can be employed. For example, one or more recesses can be formed in the optic and the force transfer assembly can be secured to the optic by having an end placed in the recess, for example, in much the same manner in which a haptic or fixation member is secured to the optic of a conventional IOL.
Any suitable material or combination of materials of construction may be utilized in the force transfer assembly and the force transfer assembly can have any suitable configuration provided that such assembly is effective to at least partially transfer the force of the eye to the optic of the IOL. The force transfer assembly preferably is more rigid or less flexible than the core of the optic. However, the force transfer assembly preferably is sufficiently deformable to be folded or otherwise deformed to pass through a small incision for insertion into the eye. The force transfer assembly can be a single member substantially surrounding the optic, or can be a plurality, for example, about 2 or about 3 to about 4 or about 6, individual elements positioned around the peripheral edge of the optic. Although the force transfer assembly can include at least one hinge to facilitate axial movement of the optic in response to the action of the eye, preferably the force transfer assembly does not include a hinge.
The force transfer assembly preferably is made of a material or materials which are compatible with the eye and with the other material or materials included in the IOL. Examples of materials which can be included in the present force transfer assemblies include, but are not limited to, polypropylene, silicone polymeric materials, acrylic polymeric materials including but not limited to polymethylmethacrylate (PMMA), polyamides and the like and combinations thereof.
In a further broad aspect of the present invention, methods for inserting an IOL in an eye are provided. Such methods comprise providing an IOL in accordance with the present invention, as described herein. The IOL is placed into the eye, for example in the capsular bag of the eye, using equipment and techniques which are conventional and well known in the art. The IOL is placed in the eye so that the eye effectively cooperates with the IOL to provide accommodation as desired. After the IOL is inserted into the eye, any incision in the eye is closed. After a relatively short period of recuperation, the IOL provides the wearer of the IOL with substantially effective accommodation. No further treatments or medications, for example, to paralyze the ciliary muscle, to facilitate fibrosis or otherwise influence the position of the IOL in the eye, are required. Preferably the optic is deformed prior to being placed into the eye. Once the IOL is placed in the eye, and after a normal period of recovery from the surgical procedure, the IOL, in cooperation with the eye, provides the mammal or human wearing the IOL with the desired accommodation.
Any and all features described herein and combinations of such features are included within the scope of the present invention provided that the features of any such combination are not mutually inconsistent.
Additional aspects and advantages of the present invention are set forth in the following detailed description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals.